1. Technology Field
The present invention generally relates to optical transceiver modules. More particularly, the present invention relates to a low-cost optical transceiver module having simplified construction and electronic scheme for longwave optical signal transmission.
2. The Related Art
Optical transceivers are used to transmit and receive optical signals from an optical network and to enable electrical network components to interface with and communicate over optical networks. Many optical transceivers are modular and are designed in accordance with industry standards that define mechanical aspects of the transceivers, form factors, optical and electrical requirements, and other characteristics and requirements of the transceivers. For example the Small Form-Factor Module Multi-Source Agreement (“SFF MSA”), the Small Form-Factor Pluggable Module Multi-Source Agreement (“SFP MSA”) and the 10 Gigabit Small Form Factor Pluggable Module Multi-Source Agreement (“XFP MSA”) Revision 3.1 define such standards.
The basic optical components of conventional transceivers include a transmitter optical sub-assembly (“TOSA”) and a receiver optical sub-assembly (“ROSA”). The TOSA receives electrical signals from a host device via circuitry of the transceiver module and generates a corresponding optical signal that is then transmitted to a remote node in an optical network. Conversely, the ROSA receives an incoming optical signal and outputs a corresponding electrical signal that can then be used or processed by the host device. Additionally, most transceivers include a rigid printed circuit board (PCB) containing, among other things, control circuitry for the TOSA and ROSA. Such control circuitry can include laser drivers and post amplifiers for conditioning the data signals handled by the TOSA and ROSA, respectively.
The TOSA and ROSA are each connected to the optical network via optical fibers that are capable of transmitting optical signals. Each optical fiber includes a connector that mates with a corresponding port defined in the respective TOSA or ROSA.
The TOSA includes a light source, such as a laser diode, that produces the optical signal transmitted via the optical fibers connected to the TOSA. The laser can be configured to transmit optical signals at one or more wavelengths. For instance, transceivers are often categorized as either “shortwave” (“SW”) or “longwave” (“LW”) transceivers, depending on the predominant wavelength emitted and/or received thereby. Examples of shortwave optical signal wavelengths transmitted by a transceiver are 780 or 850 nm; longwave transceivers can transmit optical signals having 1310 or 1550 nm wavelengths, for instance.
As the rates at which data is transmitted via communications networks rises and the cost of optical communication networks tightens, there exists an ever-increasing need to reduce costs involved in producing optical devices. One way this can be achieved is by increasing the interchangeability of components used to form optical devices, such as optical transceiver modules.
In particular, the ability to utilize common components, such as laser drivers and post amplifiers, in both longwave and shortwave transceivers represents a potentially significant savings that may be realized. Unfortunately, differences between longwave and shortwave transceiver designs often make interchangeability difficult, especially with regard to laser drivers, which often have distinct current and impedance requirements, depending on the wavelength of the optical signal to be transmitted.
As such, a need exists in the art by which optical devices, such as optical transceiver modules, can be configured such that selected components can be interchanged among different device types. In particular, it would be useful to provide the ability to utilize selected internal components, such as shortwave laser drivers, in longwave transceivers with a minimum of modification, thereby providing the ability to produce a low-cost longwave transceiver with minimum complexity.